The present invention generally relates to a stacked assembly of a plurality of modules forming an electronic or electromechanical device. More particularly, the present invention relates to an ultra-thin timepiece including such an assembly.
Stacked assemblies of a plurality of mechanical, electronic and/or electromechanical modules are known to those skilled in the art. Such assemblies are used in particular in the horological field in order to link, in the form of a stack, the different modules forming the movement of a timepiece, such as a plate, an electronic module including in particular a printed circuit board carrying various electronic and electric components of the timepiece, and, where necessary, a support bearing one or more drive means for a motion-work mechanism.
In the horological field, a solution allowing such an assembly to be achieved consists for example in stacking the various modules on mounting pins, then securing everything together, for example by riveting, i.e. by plastically deforming the end of the mounting pins. Such a solution is particularly advantageous since the assembly of the various elements forming the modules can be effected very easily and can in particular be effected automatically or semi-automatically.
Such a stacked module assembly has however a drawback in that the vertical precision of the assembly is dependent on the precision and manufacturing tolerances of the various assembled modules, in particular the thickness of the elements forming the assembly. Although it is relatively easy to manufacture certain components with a determined thickness with low tolerance, such precision and low tolerance cannot be guaranteed for each assembled module. In particular, those skilled in the art encounter great difficulty in manufacturing printed circuit boards of a guaranteed thickness within a reduced range of tolerance. If those skilled in the art wish to manufacture a timepiece incorporating a stacked module assembly as described hereinbefore, wherein at least one module includes an element of widely variable thickness, such as an electronic module including a printed circuit board, they will not be able to guarantee sufficient precision and assembly tolerance for certain applications where such precision is a necessity.
In particular, if those skilled in the art wish to manufacture a timepiece which has to answer certain strict criteria as to precision and assembly tolerance, in particular with a view to manufacturing an ultra-thin timepiece whose thickness is a critical factor, they will not be able to find, in the solutions currently available, a sufficiently satisfactory solution.
The object of the present invention is thus to propose a stacked assembly of various modules forming an electronic or electromechanical device, such as a timepiece movement, which allows account to be taken of variations in thickness of at least one constituent element of the assembled modules in order to ensure that the assembly has a determined thickness within a reduced tolerance range.
Another object of the present invention is to propose such an assembly which does not however involve any substantial complication of the assembling process and which does not increase the manufacturing costs of the assembled device.
The present invention thus concerns a stacked assembly of a plurality of modules forming an electronic or electromechanical device the features of which are listed in claim 1.
Advantageous embodiments of this assembly form the subject-matter of the dependent claims.
The present invention also concerns an electronic or electromechanical timepiece including such an assembly whose features are listed in claim 5.
Advantageous embodiments of this timepiece form the subject-matter of the dependent claims. Thus, according to a particular aspect of the invention, various modules forming an electromechanical timepiece are assembled in this manner so as to ensure that the thickness of the whole assembly has a high level of precision allowing in particular a determined clearance to be guaranteed as regards the various wheels, such as the third wheel and the intermediate wheel and/or the motion-work wheels of the timepiece movement, such clearance being necessary to allow the movement to work properly. The assembly according to the present invention is used in particular to manufacture an ultra-thin timepiece.
An advantage of the present invention lies in particular in the simplicity of its implementation. Indeed, according to the present invention, an intermediate tube-shaped element, whose outer diameter varies in discrete steps, hereinafter referred to as xe2x80x9cstepped tubexe2x80x9d, is mounted on the mounting pins of the assembly, this stepped tube being inserted in the assembly orifice of the assembled element whose thickness is not guaranteed so as to hold this element in abutment in the assembly. This stepped tube has first and second reference surfaces separated by a determined distance and against which the assembly is supported. In between these two reference surfaces, the intermediate element has a zone which penetrates the element concerned, preferably so as to cause plastic deformation of this element, the length of this zone (in the direction of assembly) being such that it allows the variations in thickness of the element to be absorbed. The two faces of the element whose thickness is not guaranteed thus do not both abut the neighbouring modules so that the thickness of the assembly is not dependent upon the thickness of this element but is determined by the two reference surfaces of the stepped tube.
According to another particular aspect of the present invention, motor coils of the electromechanical timepiece are further advantageously secured by means of the stepped tube.
The solution according to the present invention thus provides a vertical assembly of great precision without this resulting in an increase in the complexity and cost of manufacturing the assembled device.